1. Field of the Invention
The present invention relates to a radiation-sensitive composition, and a compound.
2. Discussion of the Background
Miniaturization of structures in various types of electronic devices such as semiconductor devices and liquid crystal devices has been accompanied by demands for miniaturization of resist patterns in lithography processes. Although fine resist patterns having a line width of about 90 nm can be formed using an ArF excimer laser at present, finer pattern formation is required in the future. Chemically amplified type radiation-sensitive compositions that have been broadly used for the present generate an acid upon irradiation with a radioactive ray such as a far ultraviolet light typified by a KrF excimer laser or an ArF excimer laser at light-exposed site, by a reaction with the acid as a catalyst, leading to a change in a rate of dissolution in a developer solution at light-exposed sites, whereby a resist pattern can be formed on the substrate (see Japanese Unexamined Patent Application, Publication No. 559-45439, and Perfluorooctyl Sulfonates; Proposed Significant New Use Rule).
Superior transparency to radioactive rays and a high quantum yield upon generation of an acid are demanded for radiation-sensitive acid generating agent contained in such chemically amplified radiation-sensitive compositions. Furthermore, in order to improve resolution of a radiation-sensitive composition, sufficiently superior strength of the generated acid, and a diffusion distance in the resist film (hereinafter, may be also referred to as “diffusion length”) that is short to a certain degree have been considered to be desired. Moreover, characteristics such as a sufficiently high boiling point of the acid generated, and resistance to transpiration during a heating step, etc., have been also desired.
Although a lot of acid generating agents have been developed to date, an acid generating agent that sufficiently meets the requirements described above has not yet been obtained. For example, although a radiation-sensitive acid generating agent having a trifluoromethanesulfonyl structure leads to sufficiently superior strength of the acid generated, the acid will have a low boiling point, and is accompanied by a long diffusion length; therefore, resolving performances of the radiation-sensitive composition are not satisfactory. In addition, a radiation-sensitive acid generating agent having a sulfonyl structure bonded to a great organic group such as a 10-camphorsulfonyl structure leads to a sufficiently high boiling point of the acid generated, and a short diffusion length of the acid is attained; however, a disadvantage of a difficulty in dissolving a radiation-sensitive composition containing the same in solvents generally used is involved.
On the other hand, when control of a line width of a more precise pattern should be executed as in the case in which an intended dimension of a device does not exceed a subhalf micron order, chemically amplified resists are required to be not only superior in the resolution, but also superior in smoothness of the surface of a film after formation of a resist pattern. Inferior smoothness of the surface of a film may result in deteriorated electric characteristics of a finally obtained device due to transfer of an uneven shape of the surface of the film (hereinafter, may be also referred to as “nanoedge roughness”) to a substrate in transferring the resist pattern to the substrate by a processing such as etching, consequently leading to unfavorable dimensional accuracy of the pattern (see J. Photopolym. Sci. Tech., p. 571 (1998), Proc. SPIE, Vol. 3333, p. 313, Proc. SPIE, Vol. 3333, p. 634, and J. Vac. Sci. Technol. B16 (1), p. 69 (1998)). A radiation-sensitive composition that is capable of preventing the nanoedge roughness and is superior in controllability of line widths of fine patterns has not been obtained to date.
In view of the foregoing circumstances, development of a radiation-sensitive composition that achieves high resolution, and also achieves superior smoothness of the surface of a film after formation of the resist pattern has been strongly desired.